Light electric tone pickup

ABSTRACT

In a light electric tone pick-up, a tone arm, which comprises an immovable tone arm holding member which holds the tone arm at one end pivotally about a vertical and a horizontal axis. A light beam control is disposed at the other end of the tone arm and is connected with a sensing needle for a tone modulated groove. A light source is immovably disposed adjacent to the vertical tonearm pivot axis. A first and a second light guide is secured in the tone arm, and each is directed with the cross-sectional face of one of its ends towards the light-beam control member and terminates with the cross-sectional face of the other of its ends close to the horizontal and vertical tone arm pivot axis in a radial plane, disposed spaced apart from each other, to the vertical tone arm pivot axis. Two lightelectric transmitters are immovably disposed adjacent the vertical tone-arm pivot axis and at a close distance opposite the cross-sectional faces of the light guides. A third light guide is secured in the tone arm and is directed with one of its ends towards the light-beam control member and terminates with the cross-sectional face of the other of its ends close to the horizontal and vertical tone arm pivot axis in a radial plane to the vertical tone arm swinging axis. Also, a fourth light guide is directed with one of its ends towards said light source and terminates with the other of its ends at a slight distance opposite the cross-sectional face of the fourth light guide.

United States Patent Laue [451 May 30, 1972 [30] Foreign Application Priority Data Nov. 26, 1968 Germany ..P 18 10 984.7

[52] US. Cl. ..179/l00.4 R, 179/100.4 ST, 179/100.4l L, 179/ 100.41 K [51] Int. Cl. ..G11b 3/10, H04r 5/00, l-lO4r 23/00 [58] Field of Search ..l79/100.41 K, 100.41 L, 100.4 R, 179/ 100.3 V

[56] References Cited UNITED STATES PATENTS 3,534,181 10/1970 Zimmermann ..l79/100.4 R

LIGHT ELECTRIC TONE PICKUP Black Forest, Germany Inventor:

Germany Assignee:

Filed: Nov. 25, 1969 Appl. No.: 879,693

Primary Examiner-Bemard Konick Assistant Examiner-Raymond F. Cardillo, Jr.

AI!0rne vErnest G. Montague Eckhard Laue, St. Georgen, Black Forest,

Dual Gerbruder Steidinger, St. Georgen.

[57] ABSTRACT in a light electric tone pick-up, a tone arm, which comprises an immovable tone arm holding member which holds the tone arm at one end pivotally about a vertical and a horizontal axis. A light beam control is disposed at the other end of the tone arm and is connected with a sensing needle for a tone modulated groove. A light source is immovably disposed adjacent to the vertical tone-arm pivot axis. A first and a second light guide is secured in the tone arm, and each is directed with the cross-sectional face of one of its ends towards the light-beam control member and terminates with the cross-sectional face of the other of its ends close to the horizontal and vertical tone arm pivot axis in a radial plane, disposed spaced apart from each other, to the vertical tone arm pivot axis. Two lightelectric transmitters are immovably disposed adjacent the vertical tone-arm pivot axis and at a close distance opposite the crosssectional faces of the light guides. A third light guide is secured in the tone arm and is directed with one of its ends towards the light-beam control member and terminates with the cross-sectional face of the other of its ends close to the horizontal and vertical tone arm pivot axis in a radial plane to the vertical tone arm swinging axis. Also, a fourth light guide is directed with one of its ends towards said light source and terminates with the other of its ends at a slight distance opposite the cross-sectional face of the fourth light guide.

3 Claims, 5 Drawing Figures 17 Y, 2;; 1 Ll i a t 5 1 Patented May 30, 1972 4 Sheets-Sheet 1 IN VE N TOR Eckh ard Laue Patented May 30, 1972 4 Sheets-Sheet 2 INVENTOR Patented May 30, 1972 4 Sheets-Sheet 5 Fig. 4

/N VE N TOR Eckha/ d Laue Patented May 30, 1972 4 Sheets-Sheet 4 INVENTQR Eckhord Laue LIGHT ELECTRIC TONE PICKUP The present invention relates to a light electric tone pickup, which includes a sensing needle, which is connected with a screen or mirror for the modulation of a light stream and which swings by guidance in the tone groove of a sound disc the tone arm about an axis, whereby the light source and the light-sensitive cell is immovably disposed and the light stream required for the operation is guided by means of light guides disposed in the tone arm from the light source to the modulation point in the tone arm head and to return with the intermediate arrangement of an air gap within the range of the swinging axis of the tone arm.

In accordance with a previous proposal, the arrangement of the light guides requires a comparatively large effective surface of the photo-electric cells.

It is one object of the present invention to provide a light electric tone pick-up, wherein the last mentioned drawback is avoided such, that the air gaps of at least two light guides are disposed in different rotation planes of the swinging axis of the tone arm and concentrically to the latter.

In accordance with this arrangement, it is possible, that light sensitive cells suffice, the effective surface of which corresponds about the cross section of the light guide.

It is another object of the present invention to provide a light electric tone pick-up, wherein the light guide at the end of the tone arm swinging axis is connected with a prism, which deviates by total reflection the light beam at a right angle to its longitudinal axis.

In accordance with this arrangement, a particularly space saving design of a plurality of light guides is possible within the range of the tone-arm bearing, because the bending radii conventional in light guides can be omitted.

The previous proposals for the use of light guides use the latter corresponding with an electric conduit for tone-pickups, that means, for the reproduction of stereophonic recordings at least three are required.

It is still another object of the present invention, to provide a light electric tone-pick-up, which simplifies the conduit system.

It is yet another object of the present invention, to provide a light electric tone-pick-up and in particular for a stereophonic tone-pick-up, wherein a light guide guides the light beam to be controlled from the light source to the two control edges and another light guide terminates at both of its ends in two ends, in front of which one of two different types of light filters are arranged and which, on the one hand, lead to a modulation point, on the other hand, to a photo electric cell.

It is still a further object of the present invention, to provide a light-electric tone-pick-up, wherein the stereophonic tonepick-up comprises only one light guide, which terminates at the end of the tone-arm swinging axis into three ends, of which one end leads to the light source and the two others to a light sensitive cell with the intermediate arrangement of one of two different light filters and the end of which on the tone-arm side terminates likewise into three ends, whereby the light stream of the one end is guided to the two control edges and with an intermediate arrangement of one of two difierent light filters, corresponding with the previously mentioned leads to one of the two remaining ends.

Such arrangement is characterized by a particularly small space requirement in the tone arm.

The light stream to be controlled is partly covered by a screen in the known tone-pick-up systems, which screen is connected with a sensing needle. The edge length times the amplitude performed perpendicularly to the edge results in the cross-sectional face of the changed light stream. This face is relatively small, because, on the one hand, limits are set constructively to the enlargement of the screen, first of all due to the inertia mass and, on the other hand, for the same reasons limits are also set to the amplitude size. Also the distance of the light source to the screen can be varied within certain limits.

The use of light guides for the light stream causes a certain light loss. It is an object for further development of the present invention, to increase the exploitation of the light stream. This is of course also of advantage, if no light guides are used, because with a better exploitation of the light, also the heat output of the light source can be reduced thereby.

It is still another object of the present invention, to provide a light electric tone-pick-up, wherein the screen contains at least two parallel limit edges preferably disposed cross-wise to its movement and cover strips are provided on the light sensitive surface of the cell corresponding with the number of the limit edges such, that they cover from the shade image of the screen the necessarily created rear edges within the range of its maximum amplitude.

In accordance with this arrangement, it is possible, upon provision of a plurality of limit edges, relative the previously known arrangement, to obtain a corresponding multiple light current variation with the same amplitude.

In order to obtain an optimum exploitation of the surface of the light sensitive cell, in accordance with a further development of the present invention, it is provided that the material remaining between the limit edges corresponds as to its width to about the half distance of the limit edges.

With these and other objects in view, which will become apparent in the following detailed description, the present invention, which is shown by example only, will be clearly understood in connection with the accompanying drawings, in which:

FIG. 1 is a side elevation of a tone arm bearing in section; FIG. 2 is a fragmentary section along the lines 2-2 of FIG.

FIG. 3 is a fragmentary view of the structure shown in FIG. 1, and

FIGS. 4 and 5 are schematic views of the most important parts of two different light electric stereo tone-pick-ups.

Referring now to the drawings, and in particular to FIG. I, in a base plate 1 is secured a bearing carrier 2. In the latter is mounted rotatably in points 5 and 6 about a vertical axis 3 (tone-arm-swinging-axis), a tone-arm-carrier 4. The tone arm 7 is rotatably mounted with point bearings 8 and 9 about a horizontal axis 10 in the tone-arm-carrier 4. In the bearing carrier 2 an incandescent bulb 11 is secured. Opposite therefrom, a light guide 12 is secured to the tone-arm-carrier 4, swinging with the tone arm 7, which light guide 12 leads to the direct vicinity of the horizontal swinging axis 10 of the tone arm 7, and with the intermediate arrangement of an air gap 13 is continued in the tone arm 7 by means of a prism 14. During swinging of the tone arm 7 above its swinging axis 3, the light guide 12 rotates at its lower end merely about its longitudinal axis and remains thereby in its position relative to the light bulb 11. Within the range of air gap 13, no change takes place.

The light which is modulated in form of a channel (not shown) in the tone arm head is fed by means of the two light guides 16 and 17, to the prisms l8 and 19 of synthetic material attached thereto and the air gap 20 and 21 to the light sensitive cells 22 and 23. The latter are immovably arranged by means of a holding arm 24 on the bearing carrier 2. Due to the concentric position of the prisms 18 and 19 to the swinging axis 3 of the tone arm 7, the prisms do not change their position relative to the photo electric cells 22 and 23, if their tone arm is turned horizontally.

In accordance with FIG. 4, a light bulb is provided in the base plate 30 as a light source 31 and as a light sensitive cell 32 and 33, two photodiodes are provided. Opposite to the latter terminates a likewise immovably disposed three armed light guide 34, which is disposed with its main part in the vertical tone arm swinging axis 35. By means of a prism 38 disposed tightly thereover and connected with the light guide 37 disposed in the tone arm 36 the light beam is fed to the tone arm head 39. One end 40 of the likewise three armed terminating light guide 37 leads the light stream back over a prism 41 and 42 to the two other ends 43 and 44. In the open way of the light is disposed a control edge 45 and 46 of a screen connected with the sensing needle 47 each. The oppositely disposed ends of the light guide are arranged in pairs and are equipped with a red 43, 49 and a green filter 44, 48, respectively.

A variation for instance of the light beam impinging by example upon a filter 43 in the rhytm of the movements of the sensing needle 47 causes a variation of the light falling backwardly in the light guide 34 and 37 and in particular only the one which corresponds with the red color filter 43. This variation can urge towards the outside of the light guide only there, where the particular light color is passed, that means, on the red filter 49, not, however, on the green filter 48. The back stream of the light towards the light source 31 is thereby without any significance. The different return feeding of the light in two different colors on the same path without reciprocal influencing and with separation at the exit point 49 and 48, respectively, where the light sensitive cells 32 and 33 are arranged, in addition to the feeding of the light beam the simultaneous transmission of both stereo channels to one and the same light guide results.

In accordance with FIG. 5, a light source 50 is disposed in the tone arm head, the light stream of which is directed towards two light sensitive cells 51 and 52. To the arm 53 of a sensing needle 54 is secured a light screen 55, which covers partly the light sensitive cells 51 and 52 against the light beam. Parallel to the control edges 56 and 57 disposed in the two modulation directions A and B, the screen contains a slot 58 and 59. The light sensitive cell 51 and 52 carries a light nontransparent strip 60 and 61. It is arranged to the corresponding slot 58 and 59 of the screen 55 such, that it covers by the shadow image 55 of the screen 55 on the light sensitive cell 51 and 52 the slot edge 64' disposed close to the control edge 56 and 57.

If the sensing needle 54 and the screen 55, respectively, is moved upwardly in the modulation direction A," the lit face of the light sensitive cell 52 likewise not covered by the shade image 55' of the screen 55 is reduced. The face lit through the slot 59 of the screen 55 is likewise reduced, because the lower slot edge 62 and 62', respectively, approaches the lower edge 63 of the light non-transparent strip 61. The change amount, namely the edge length 57, 62, times amplitude, occurs twice corresponding with the number of the edges 57 and 62, which causes in this case a doubling of the current variation. It is to be understood, that a further multiplication with, the addition of further slots 50 and covering strips 60 and 6], respectively, is possible.

While we have disclosed several embodiments of the present invention, it is to be understood that these embodiments are given by example only and not in the limiting sense.

I claim:

1. In a light electric tone pick-up,

a tone arm,

immovable tone arm holding means holding said tone arm at one end swingably about a vertical tone-arm swinging axis and a horizontal tone-arm swinging axis,

light-beam control means disposed at the other end of said tone arm,

a sensing needle for a tone-modulated groove connected with said light-beam control means,

a light source immovably disposed adjacent to said vertical tone-arm swinging axis,

a first and a second light guide secured in said tone-arm,

each of said first and second light guides being directed with the cross-sectional face of one of its ends towards said light-beam control means and terminating with the crosssectional face of the other of its ends close to said horizontal and vertical tone arm swinging axes and in a plane disposed parallel to said vertical tone arm swinging axis and said cross-sectional faces of said one ends being spaced from each other,

two light electric elements immovably disposed adjacent said vertical tone-arm swingin axis and at a close distance opposite said cross-sectional faces of said light guides,

a third light guide secured in said tone arm and directed with one of its ends towards said light-beam control means and terminating with the cross-sectional face of the other of its ends close to said horizontal and vertical tone arm swinging axes and in a plane parallel to said vertical tone arm swinging axis, and

a fourth light guide directed with one of its ends towards said light source and terminating with the other of its ends at a slight distance opposite said cross-sectional face of said third light guide.

2. The light-electric tone arm pick-up, as set forth in claim 1, wherein said ends of said light guides secured to said tone arm, on the side of said tone arm holding means are connected each with a prism, which deviates by total reflection the light beam at a right angle 3. The device, as set forth in claim 1, wherein at least two of said cross-sectional faces of said one ends of said light guides in said tone arm are spaced from said vertical tone arm swinging axis by different radial distances, respectively. 

1. In a light electric tone pick-up, a tone arm, immovable tone arm holding means holding said tone arm at one end swingably about a vertical tone-arm swinging axis and a horizontal tone-arm swinging axis, light-beam control means disposed at the other end of said tone arm, a sensing needle for a tone-modulated groove connected with said light-beam control means, a light source immovably disposed adjacent to said vertical tone-arm swinging axis, a first and a second light guide secured in said tone-arm, each of said first and second light guides being directed with the cross-sectional face of one of its ends towards said lightbeam control means and terminating with the cross-sectional face of the other of its ends close to said horizontal and vertical tone arm swinging axes and in a plane disposed parallel to said vertical tone arm swinging axis and said cross-sectional faces of said one ends being spaced from each other, two light electric elements immovably disposed adjacent said vertical tone-arm swinging axis and at a close distance opposite said cross-sectional faces of said light guides, a third light guide secured in said tone arm and directed with one of its ends towards said light-beam control means and terminating with the cross-sectional face of the other of its ends close to said horizontal and vertical tone arm swinging axes and in a plane parallel to said vertical tone arm swinging axis, and a fourth light guide directed with one of its ends towards said light source and terminating with the other of its ends at a slight distance opposite said cross-sectional face of said third light guide.
 2. The light-electric tone arm pick-up, as set forth in claim 1, wherein said ends of said light guides secured to said tone arm, on the side of said tone arm holding means are connected each with a prism, which deviates by total reflection the light beam at a right angle
 3. The device, as set forth in claim 1, wherein at least two of said cross-sectional faces of said one ends of said light guides in said tone arm are spaced from said vertical tone arm swinging axis by different radial distances, respectively. 